Vibrating screen



Oct. 26 1926. 1,604,324

G. M. STEDMAN VIBRATING SCREEN Filed March 27, 1925 2 Sheets-Sheet l I I @2313 K Oct. 26 1926.

G. M. STEDMAN VIBRATING SCREEN 2 Sheets-Sheet 2 Patented Oct. 26, 1926 l,til4,324

arena? GEORGE 1VI. STEDMAN, OF AURORA, INDIANA.

VTBB/ATING SCREEN.

Application filed March 2'7, 1925. Serial No. 18,858.

My invention relates to a vibratory screen, for screening granular materials.

One of the objects of the invention is to provide a vibratory mechanism which can be compactly arranged and housed to keep the controlling cam constantly lubricated and protected from the atmosphere of line dust and suspended abrasive particles.

Another object of the invention is to provide a simple and efficient species of vibratory elements particularly designed to produce an action wherein the screen is gradually raised to its maximum vertical position and then suddenly dropped or snapped back to the lowest position with a jolt or impact, this gravity-drop action being preferably accentuated by coordinating there with a resilient screen-agitating instrumentality.

Another object of the invention is to provide a vibrating yoke superposed in relation to the screen enabling the power shaft and its cam or tappet rotary member to be sup ported in relation to the bridge member of the yoke, the lower end of the yoke extending to the plane of the screen and engaging a resilient agitator disposed along the medial line of the under surface of the screen. Preferably also I provide a spring pressed lever of the compression or tension type of spring for engaging said agitator to normally hold the medial portion in depressed position.

Another object of the invention is to so yieldingly attach the screen margins to the side members of the supporting; frame that the screen will have a unitary flexation in a plane transverse to the plane of the tagpet or agitating action.

This marginal spring support for the screen has the additional advantage of providing securance in the nature of a clamp or grip upon the marginal portion of the screen which will prevent rupture of the screen when stressed by the tappet or vibratory action and which will also constitute a convenient means for attaching and detaching or adjusting the screen.

I am aware that this tappet order of vibrating screen is not broadly new, many forms differing from mine having been heretofore employed, for instance, such a con-' struction as is exemplified in the Leahy Patent No. 1,456,067, of May 22nd, 1923, m which the tappet engages the upper screen to protect the operative parts from the abrasive dust and at the same time afford adequate lubrication. When the actuating mechanism which is exposed to this dust is lubricated, the dust or abrasive particles working into the lubricant make a grinding action which rapidly wears the operative parts.

I have been able to effectually solve this problem and to overcome this difficulty in a very satisfactony manner by the provision of the superposed vibratory yoke herein disclosed, providing as it does for the complete protection and lubrication of the operative mechanism.

Other features and certain advantages will be more fully set forth in the description of the accompanying drawings forming a part of this specification, in which:

Figure 1 is a plan view of the screen.

Figure 2 is a side view thereof.

Figure 3 is an enlarged sectional view on line 33 of Figure 1..

Figure 4 is an enlarged sectional view on line a l of Figure 1, showing the mechanism for vibrating the screen.

Figure 5 is a detailed sectional view on line 55 of Figure 1.

The shape of'the frame is immaterial, but I have shown for my purpose a rectangular marginal frame or bed 1, preferably disposed approximately in horizontal plane. although it may be tilted if desired. In this frame is secured the screen 2, the detail securing members being shown in Figure 3, as comprising a spring plunger or pin 3 passing through the side frame pieces, the coil spring being interposed between the exterior of the frame piece and the bolt nuts 5. On the other end of the pin 3 within the frame is the bracket 6. The margins of the screen are held between the uneven surfaces of the bottom clamping block 7 and top clamping block 8, the uneven surfaces being of irregu lar or grip formation. These blocks 7, 8, with the screen gripped between these surfaces, are held as a unit upon the brackets 6 and the spring plungers 3 by means of bolts 9, These blocks are preferably of wood or compressible material which will not too harshly impinge upon the screen and these blocks and spring plungers are distributed adjacent one another upon opposite sides of the frame as shown in Figure 1.

From this construction it will be seen that when the medial portion of the screen is depressed, the opposite margins of the screen move toward one another, so that when the spring is vibrated in the plane of the tappet action there is a constant and corresponding movement of the screen in the transverse plane permitted by this spring plunger method of supporting the opposite margins of the screen in relation to this frame.

The vibrating yoke consists of a U-shapcd frame superposed in relation to the main frame and comprising a link 10 and bridge 11 disposed in the medial longitudinal hne of the screen. The bridge member 11 of the yoke has a centrally disposed bearing plate 18 for engagement with the rotary member or cam wheel 16. Each link of the yoke has a depending bracket 17 extending to the plane of the screen. The brackets 17 are preferably pivotally connected to or suspended from the lower enrjls of the yoke links. Strictly speaking, the brackets are supported upon the agitator which extends under the screen and the yoke is supported upon and by the brackets. in the central longitudinal line of the frame and below the screen is a resilient agitating member 19, approximating bow-like contours as it is preferably formed of resilient wood intended to vibrate at the middle portion which is attached to brackets 17, its opposite ends being secured to the end portions of the frame. This resilient agitator 19 is connected or operatively engages the under surface of the screen so that it moves, or at least the medial portion of it moves unitarily with the yoke. This resilient agitator 19 is preferably held normally in its depressed position under spring tension administered through a lever 20 intermediatel fulcrumed, the inner end 21 of which is con nected to the member 19, and the outer end of which is under pressure by the spring 21' (see Figure 2), this spring pressing the outer end of the lever normally upward and therefore urging the inner end of the lever normally downward. superposed transversely and medially upon frame 1 is a second frame 30 comprising end brackets 12 and cross beams 13 and a cross head 14 carrying the lubricating trough and 'roviding bearings 15 for the drive shaft 25.

The cross head 14 (see Figure 4:) carries at its medial portion the housing or lubricating trough 24 through which extends the driving shaft 25 supported in suitable bearings 15 on the cross head 14:. On the housed portion of th s driving shaft is placed the cam wheel or rotary member 16 having its periphery formed cam-like to engage the bearing plate 18, the cam surface being characterized by the abrupt shoulder 27 which in the direction of rotation shown in Figure 41, slowly raises the yoke to a maximum vertical position at the time the shoulder 27 engages the bearing plate 18, and as this shoulder leaves the caring plate the entire yoke drops bodily and abrupty under the combined influence of gravity and the spring pressure of the lever 20.

By the construction of the oil trough 21 for the cam wheel 16, I am able to keep a constant supply of luln-icant therein and 1 also preferably employ as closures the bracket plates 28 adjacent the opp 'te sides of the bearing plate 18 which completely house in this portion of the shaft and the operating cam. The yoke links have vertical guides 29 in relation to the cross-head.

Owing to the complete lubrication of th s device and its protection from abrashc dust, as well as owing to the su 'ierposcd relationship of the cam and driving shaft and also very largely because of the spring or resilient connection between the underside of the yoke and the under surface of the screen, the screen being in turn springa'ttachcd to the margins of the frame in a plane transverse to the tappet or vibratory action, it is possible to very materially speed up the operation of the drivingshaft and. the can) to give a high rapidity vibratory action to the parts characterized by the relatively slow rising motion of the medial Zone of the screen and its sharp return. This action on the abrasive material is very much like tossing in the air or dropping the screen or bottom from under it quickly so that the abrasive material is suspended andv drops with an impact upon the screen in its lowermost position. The screening operation is not only improved or rendered more efficient by this particular action but the result is materially improved and the separation action quickened by this organiza tion which permits a relatively high speed of vibration made possible where the parts are sufficiently lubricated and protect l and where there are no rupturing stress s upon the screen itself, due to the fact the vibratory action is of a spring nature and the spring influence is exerted 'in these transverse planes. Also this method of supporting and operating the screen n'rserves the life and efficiency of the screen. Preferably I provide the adjust: 31 in the cross head and stoos I placed under the middle of the yoke which may ie set to lim t the length of the drop to less dimension than the drop provided by the height of the shoulder 27. Various means may he provided for rotating the yoke and for connecting it to the medial. zone of the screen without departing from the principles disclosed in the particular embodiment of the ilh 1stration.' v,

I'Iaving' described my invention, I claim:

1. In combination with a marginal frame and a screen to be vibrated, a superposed yoke having member medially bridging the frame, formed with a medial bearing plate and with depending brackets, a resilient agitator connected to said brackets and engaging a medial portion of the under-surface of the scrcei'i, a power shaft assing through the yoke and under its bridge member, and a rotary member on the shaft having an irregular-periphery engaging the plate for vibrating the yoke, agitator and screen.

2. In combination with a marginal frame and screen to be vibrated, a superposed yoke having a member medially bridging the frame and formed with a centrally positioned bearing plate, a resilient agitator below the screen, the ends of which are secured to the frame, the medial portion of said agitator being connected to the lower ends of the yoke, a power shaft passing through the yoke and under the bridge member, and a rotary member on the shaft hav ing an irregular periphery engaging the said bearing plate of the yoke.

3. In combination with a marginal frame and screen to be vibrated, a superposed yoke having a member bridging the frame and formed with a medially positioned bearing plate, brackets depending from the ends of said yoke, a resilient agitator below the screen, the ends of which are secured to the frame, means connecting the medial portion of said agitator with said brackets depend ing from said yoke, a power shaft passing through the yoke and under the bridge member, a rotary member on the shaft having an irregular periphery engaging the said bearing plate of the yoke, and a lubrication trough member suspended adjacent the medial portion of said yoke and forming a housing in which the said rotary member operates.

4. In combination with a marginal frame and screen to be vibrated, a superposed yoke having a member medially bridging the frame transversely and formed with a medially positioned bearing plate, brackets depending from the said yoke, a resilient agitator below the screen, the ends of which are secured to the frame, means connecting the medial portion of said agitator with said brackets, a power shaft passing through the yoke and under the bridge member, a rotary member on the shaft having an irregular periphery engaging the said bearing plate of the yoke, a suspended lubricating trough for the under periphery of said rotary member, and a spring actuated lever supported by the main frame and having one end engaging the medial portion of said spring actuator for normally depressing the medial zone of the screen.

In combination with a marginal frame and a screen to be vibrated, a stationary cross member medially bridging the frame, a superposed yoke having a member transversely bridging the cross member, formed with a medial bearing plate and with brackets, a resilient screen agitator supported at its ends by said frame, said brackets engaging a medial portion of the agitator, said agitator extending in the plane of the yoke, a power shaft passing transversely through the yoke and under its bridge member, a rotary member on the shaft having an irregular periphery engaging the yoke plate for vibrating the agitator and screen, adjustable stops on the stationary cross member below said bridging member of the yoke for engaging the underside of the yoke for controllin the vibratory movement of said yoke,- and means for connecting the opposite margins of the screen to the corresponding side pieces of the frame consisting of spring controlled members permitting the opposite margins of the spring to vibrate in a plane transverse to the movement of the yoke.

(3. In combination with a marginal frame and a screen to be vibrated, means yield ingly securing the opposite margins of the screen to the opposite side pieces of said frame, a stationary cross member medially bridging said frame, a yoke superposed in a transverse relation to the stationary cross member, means connecting the lower extremities of the yoke to the medial zone of the screen, a shaft extending medially and longitudinally below the superposed portion of the yoke, a cam on the shaft for engaging the underside of the yoke for vibrating the same, and adjustable stops on the stationary cross member for engaging the yoke for controlling the vibratory movement of said yoke and resilient member.

7. In a device of the class described, in combination with a main frame, a screen to be vibrated, means for yieldingly attaching the opposite margins of the spring to the opposite side pieces of said frame, a resilient agitator, the ends of which are secured to the end pieces of the frame below the screen, the medial portion of said agitator being operatively engaged. with the under-surface of the screen, a spring mechanism supported on the frame holdin the medial portion of said agitator in depressed position, and a vibratory mechanism positioned above the screen and operatively connected to the media]. portion of said vibrating member below the screen.

8. In a device of the class described, in combination with a main frame, a screen to be vibrated, means for yieldingly attaching the opposite margins of the spring to the opposite side pieces of said frame, a resilient agitator, the ends of which are secured to the end pieces of the frame below the screen, the medial portion of said agitator being operatively engaged with the under-surface of the screen, a spring mechanism supported on the frame holding the medial portion of said agitator in depressed position, a vibratory mechanism positioned above the screen and operatively connected to the medial portion of said vibrating memher below the screen, said superposed vibratory mechanism comprising a power shaft and a cam Wheel thereon, and means constituting a housing and lubricating trough in which said \vheel operates.

9. in a device of the class described, a narginal frame and a screen to be vibrated, the opposite margins of said screen being yieldingly attached to opposite side pieces of the frame, a vibratory yoke superposed over the medial portion of the screen having a bearing plate, a shaft and cam \vheel above the screen passing through the yoke, means forming an oil trough and housing Within vvhich said cam operates, said cam engaging said bearing plate and being in the form of an abrupt shoulder to drop the yoke bodily, brackets depending from said yoke, a resilient agitator below the screen and engaging the medial portion thereof, means connecting the medial portion of said agitator to the depending yoke brackets, and spring actuated means engaging the main frame coacting to hold said vibrating resilient actuator in its depressed position.

10. In a device of the class described, a main frame, a screen to be vibrated, a resilient agitator extending medially and longitudinally of said frame andengaging said screen, a superposed yoke having a member medially bridging the frame and depending member secured to said resilient agitator, vibrating means under said yoke for shaking the screen, and a lever fulcrume-d on the frame beneath the resilient agitator, said lever having one end attached to said resil- Leo r324 ient agitator and the other end spring activated. and said lever depressing the medial Zone of the screen for increasing the vibra tion of the screen.

11. In a device of the class described, a main frame, a screen to be vibrated, a resilient agitator extending longitudinally of the frame and engaging the screen, a superposed yoke attached to said resilient agitator, a power shaft extending through said si'zperpoited yoke, a rotary member on said shaft havii an irregular periphery engaging the enter side of said yoke, and a spring actuated lever medially engaging said resilient a ate}: for depressing the screen and hastening the fall of the yoke as the rotating member is activated to increase the vibration of the screen.

12. In combination with a marginal frame and a screen to be vibrated, a superposed yclie medially and transversely bridging said frame and formed with members, depending helovv the plane of the screen, means resiliently connecting said depending yoke ends with the medial Zone of the screen, a second frame placed on the. main frame and extendne; medially and transversely thereto proiding a cross-head extending under the idgin portion of said yoke, a power shaft jonrnaled in hearings on said cross heads, a cam on said shaft engaging a bearing on the bridging portion of the yoke, and a lubricating trough for the cam Wheel formed in a portion of said cross head.

13. In a pulsating screen, a frame, a screen tautly sustained Within the frame, a resilient bar extending medially of and beneath the screen and secured at its opposite ends to the frame and engaged with the screen, ten sion means for said bar having a lever connection therewith, and means for intermittently agitating said bar for forcibly setting up bar vibration and screen pulsation.

In Witness whereof, I hereunto subscribe my name.

GEORGE M. STEDMAN.

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